Reconstructive surgery has been used for many years for the treatment of congenital tissue defects and for repair of damaged organs and tissues. An ideal material for tissue reconstruction should be biocompatible, able to incorporate into the native tissue without inducing an adverse tissue response, and should have adequate anatomical and functional properties (for example, size, strength, durability, and the like). Although a large number of bio-materials, including synthetic and naturally-derived polymers, have been employed for tissue reconstruction or augmentation (see, e.g., "Textbook of Tissue Engineering" Eds. Lanza, R., Langer, R., and Chick, W., ACM Press, Colorado (1996) and references cited therein), no material has proven satisfactory for use in every application.
For example, in the field of bladder reconstruction, synthetic biomaterials such as polyvinyl and gelatin sponges, polytetrafluoroethylene (Teflon) felt, and silastic patches have been relatively unsuccessful, generally due to foreign body reactions (see, e.g., Kudish, H. G., J. Urol. 78:232 (1957); Ashkar, L. and Heller, E., J. Urol. 98:91 (1967); Kelami, A. et al., J. Urol. 104:693 (1970)). Polymeric materials have been used as "scaffolds" for seeding cells; the seeded scaffolds can be implanted to provide a matrix for the growth of new tissue (see, e.g., Atala, A. et al., J. Urol. 148 (2 Pt 2): 658-62 (1992); Atala, A., et al. J. Urol. 150 (2 Pt 2): 608-12 (1993)). Naturally-derived materials such as lyophilized dura, de-epithelialized bowel segments, and small intestinal submucosa (SIS) have also been proposed for bladder replacement (for a general review, see Mooney, D. et al., "Tissue Engineering: Urogenital System" in "Textbook of Tissue Engineering" Eds. Lanza, R., Langer, R., and Chick, W., ACM Press, Colorado (1996)).
It has been reported that bladders augmented with dura, peritoneum, placenta and fascia contract over time (Kelami, A. et al., J. Urol. 105:518 (1971)). De-epithelized bowel segments demonstrated an adequate urothelial covering for use in bladder reconstruction, but difficulties remain with either mucosal regrowth, segment fibrosis, or both. It has been shown that de-epithelization of the intestinal segments may lead to mucosal regrowth, whereas removal of the mucosa and submucosa may lead to retraction of the intestinal segment (see, e.g., Atala, A., J. Urol. 156:338 (1996)).
Xenogenous porcine SIS has been used recently with favorable results (e.g., Kropp, B. P. et al, Urology 46:396 (1995)). This biodegradable collagen-rich xenogenic membrane had been previously studied as a potential material for vascular grafts (see, e.g., Hiles et al., J. Biomed. Materials Research 27:139 (1993)). However, SIS may be limited by the maximum size the graft can cover, which may not be sufficient for bladder replacement.
Other problems have been reported with the use of certain gastrointestinal segments for bladder surgery, including infection, perforation, stone formation, metabolic derangements and instances of tumor development. Formalin-preserved sections of bladder have been used for bladder reconstruction (see, e.g., Tsuji et al., J. Urol. 98:91 (1967)). However, the use of the formalin-preserved material generally did not result in effective long-term treatment.
Polymeric and naturally-derived "scaffolds" have also been used to support the regrowth of bone into bone defects (see, e.g., U.S. Pat. Nos. 5,112,354 and 4,172,128; for a general review, see Yaszemski, M. J.; et al., Biomaterials 17 (2): 175-85 (1996) and references cited therein). Bone-derived collagen implants have been used for bone repair. However, these materials do not always provide the requisite strength, flexibility, or non-immunogenicity needed for long-term repair of bone.